Access control mechanisms for outsourced data in public cloud using polynomial interpolation and multilinear map

Abstract

Outsourcing the user's sensitive data on to honest-but-curious cloud storage servers pose several data security and access control challenges. Single key and multi-key encryption strategies to protect the data require data owner participation for providing access to data and management of multiple keys by users. To reduce the key management at the users and to remove data owner's participation during data accesses, we propose three access control schemes: 1) based on the principle of polynomial interpolation; 2) using multilinear map; 3) dynamic access control scheme using multilinear map. The security of multilinear map based schemes relies on the multilinear Diffie-Hellman assumption. The key generated for data encryption is regulated by the access authorisations holding on the data. In all the proposed schemes, the authorised user needs to store only one key irrespective of the number of data items to which the user has authorised access and do not require the data owner's participation except in grant and revoke operations.